Maintenance Plan - History Cleanup Task

This is a note to all who use the Maintenance Plan Task: History Clean Up.
I have several small databases housed on one SQL 2005 server. I intended to keep historical data about most of the databases for 6 months and 1 in particular db for only 1 month. The clean up for the 1 month database removed ALL of my history collected from other 6 month databases.
I broke down the job using the View T-SQL button and recieved the following:
declare @dt datetime select @dt = cast(N'2007-06-19T11:59:56' as datetime) exec msdb.dbo.sp_delete_backuphistory @dtGOEXEC msdb.dbo.sp_purge_jobhistory @oldest_date='2007-06-19T11:59:56'GOEXECUTE msdb..sp_maintplan_delete_log null,null,'2007-06-19T11:59:56'

My main question how did SQL Server generate the date? I wrote a script this actually prints the date, hoping to use a sp to return a date but can not get the date to RETURN from the stored procedure execution: